Acetylene solution



United States Patent 0. R

ACETYLENE. SOLUTION Theodor Reetz, St. Louis, Mo., assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application May 17, 1954, Serial No. 430,416

8 Claims. (Cl. 183-115) This invention relates to acetylene and more specifically to acetylene solutions. This invention also relates to the recovery of acetylene from an acetylene-containing gas by means of a selective solvent.

It is known in the art that various organic compounds have shown utility as selective solvents for acetylene, thereby afiording means for storing acetylene in the form of solutions of acetylene in the solvents and means of extracting acetylene from gas mixtures or increasing the acetylene content of such gas mixtures.

It is an object of this invention to provide a class of solvents having exceptional utility in the aforementioned applications. Other objects will become apparent from the description of this invention.

It has now been discovered that dialkyl acetylmeth'anephosphonates, as represented by the formula OR (lHaCOCHr-i wherein R is an alkyl group containing from 1 to 3 carbon atoms, are excellent solvents for acetylene.

The Bunsen coefficients (volume of gas, measured at 0 C. and 760 mm. Hg, dissolved, at the temperature of the experiment, in one volume of solvent at a gas partial pressure of 760 mm. Hg) for acetylene in these solvents indicate their excellent solvent action for acetylene. The Bunsen coefficients (ca were determined in the following manner:

A quantity of acetylene was introduced into a calibratcd flask and its initial pressure pi (measured to 0.05 mm. Hg), initial volume V1 (measured to $0.05 ml.), and initial temperature T1 (measured to i0.02 C.) determined. A quantity of solvent Was then added to a second calibrated flask and its volume mls and vapor pressure P5 determined. The acetylene was then transferred to the flask containing the solvent and, after agitation, the temperature of the liquid was brought to a temperature of 25 :0.005 C. and the temperature of the gas was brought to a temperature of 25.3:005" C. The pressure pr of the gas, volume V: of the gas and temperature T: of the gas were then determined. 11 was then calculated as follows:

2,800,979 Patented July 30, 1957 2 where ds=density of solvent at 25 C. M Ws=molecular weight of solvent a760 Z; p,- P- In accordance with the procedure outlined above, the

Bunsen coeflicient for acetylene at 25 C. in diethyl acetylmethanephosphonate was found to be 16.13. A

comparison of this value with the value of 13.6 found for -butyrolactone, a well known acetylene solvent, demonstrates that diethyl acetylmethanephosphonate is an efiective solvent for acetylene. correspondingly high Bunsen coeflicients for acetylene are to be found for.dimethyl 'acetylmethanephosphonate and dipropyl acetylmethanephosphonate.

According to the invention, diethyl acetylmethanephosphonate is most efliciently used in the extraction of acetylene from diluted acetylene such as is obtained by the partial oxidation of low molecular weight hydrocarbons. As an example, dilute acetylene obtained from the partial oxidation of methane with oxygen has the following composition:

This gas stream is treated under pressure with the aforementioned solvents in any convenient manner well known to those skilled in the art as, for example, by countercurrent absorption in the solvent. The solution of acetylene is then transferred to a suitable desorption column where the pressure is released and the temperature raised. Concentrated acetylene is thus obtained and any contamination of the acetylene with the solvent is so small as to be insignificant.

In addition to the utility of the solvent of the invention in the extraction of acetylene from diluted acetylene, the Bunsen coefiicicnts of these solvents clearly indicate that they are particularly suited for storing acetylene under elevated pressures.

The solvents described herein may be used per se, or they may be used in mixtures with other acetylene solvents.

The term consisting essentially o which appears in the claims hereof is intended to refer to a composition in which the total amounts of the components set forth in the claim constitute the predominant proportion in the composition. Such term is not intended to exclude the presence of materials such as moisture or water, or other material which may be present as an inert diluent and does not adversely alfect the solution in any manner. However, the term is intended to exclude the presence of materials which so change the character of the composition that it can no longer be regarded as a solution of acetylene.

What is claimed is:

l. A composition of matter consisting essentially of a solution of acetylene in a dialkyl acetylmethanephosphonate of the formula CHsCOCHs-i' wherein R is an alkyl group containing from 1 to 3 carbon atoms.

2.- A composition of matter consisting essentially of a solution of acetylenein diethyl acetylmethanephosphonate.

3. A composition of matter consisting essentially of a solution of acetylene in dimethyl acetylmethanephosphonate.

4. A composition of vmatter consisting essentially of a solution of acetylene in dipropyl acetylmethanephosphonate.

5. In a process for the recovery of acetylene from an acetylene-containing gas, the step of contacting said gas witha dialkyl acetylmethanephosphonate of the formula onto OCHri wherein'R is an alkyl group containing from 1 to 3 carbon atoms. 1

6. In a process for the recovery of acetylene from acetylene-containing gas, the step of contacting said gas with diethyl acetylmethanephosphonate.

7. In a process for the recovery of acetylene from an acetylene-containing gas, the step of contacting said gas with dimethyl acetylmethanephosphonate.

8. In a process for the recovery of acetylene from an acetylene-containing gas, the step of contacting said gas with dipropyl acetylmethanephosphonate.

References Cited in the file of this patent UNITED STATES PATENTS 2,431,676 Bour Dec. 2, 1947 2,580,622 Vogt et a1. Jan. 1, 1952 2,623,611 Levineiet a1. Dec. 30, 1952 2,642,956 Bour June 23, 1953 2,667,234 Hasche Jan. 26, 1954 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALY OF A SOLUTION OF ACETYLENE IN A DIALKYL ACETYLMETHANEPHOSPHONATE OF THE FORMULA 